Generally, a magnetic recording medium is prepared by coating on a support a magnetic paint comprising a magnetic powder and a binder resin, followed by drying. In conventional magnetic recording media comprising a single layer, a broad frequency region from low to high range must be covered by only one magnetic layer. Particularly in the recent trend toward high density recording where a higher recording performance and lower noise in a high frequency range are required, there is used a magnetic powder having a high Hc and a high BET value.
In this case, however, the characteristics in a lower frequency range are sometimes liable to be unsatisfactory.
The magnetic recording media for a video tape having plural magnetic layers in order to increase a recording capacity and balance the magnetic recording properties in both high and low frequency ranges are disclosed in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 98803/1973, 172142/1984, 64901/1976, 56228/1983, 146211/1988, and Japanese Patent Examined Publication Nos. 2218/1957 and 12937/1981.
The magnetic recording media in which there is limited a coercive force (Hc) of a ferromagnetic powder contained in each of plural magnetic layers are disclosed in Japanese Patent O.P.I. Publication Nos. 56228/1983, 5623/1983 70429/1983 and 106333/1989. These conventional techniques, however, are not necessarily sufficient for providing required output over a wide frequency region from low to high range.
Other proposals are directed to the techniques in which surface roughness of a magnetic layer is made smoother or controlled to a prescribed level to decrease a spacing loss between a magnetic layer surface and a magnetic head for preventing deterioration of recording characteristics especially in a high frequency range and achieving excellent electromagnetic conversion properties, as disclosed in Japanese Patent O.P.I. Publication Nos. 168124/1986, 143522/1981, 143523/1981 and 150130/1982.
However, measures to merely reduce the surface roughness of a magnetic layer are liable to result in a larger friction coefficient which will generate rubbing noise when the recording medium contacts a magnetic head or run in a cassette deck. On the contrary, an increased surface roughness deteriorates electromagnetic conversion properties while it reduces rubbing noise.